The present invention relates to a method and a system for controlling an automated friction clutch situated between an engine and a transmission of a motor vehicle.
A peculiar feature of piston combustion engines is that the torque loading on the crankshaft becomes increasingly irregular as the number of cylinders and the rotational speed decrease. This has a negative effect on driving comfort. An effective possibility for reducing vibrations caused by rotational inconsistencies is presented by the dual mass flywheel, which however entails additional expense compared to a single-mass flywheel and requires a certain amount of mounting space.
In recent times, the use of automated friction clutches that enable improvement in operating comfort and allow the use of economically favorable automated manual transmissions has become more widespread.
DE 41 90 372 proposes a method for controlling such an automated friction clutch in such a way that it may be adjusted or regulated to a slip having a predetermined magnitude in order to decrease torsional vibrations. For this purpose a clutch torque computation device is provided that computes a clutch torque to be transferred based on engine torque and in some instances further operating parameters of the vehicle's drive train and determines from this a control signal for actuating a controller of the clutch. A setpoint slip computation device is further provided, in which a setpoint slip of the clutch is stored as a function of the operating state variables of the drive train. This setpoint slip is compared with an actual slip of the clutch. An additional control signal for the clutch controller is derived from this comparison in a PID controller, the control signal being superimposed by the control signal dependent on the clutch torque to be transferred. To improve control quality, the integral part of the PID controller is used together with additional operating state variables to modify the torque to be transferred by the clutch.